seating depth, vibratory pattern and muzzle velocity

[solst_ice]

When I develop a load for my .308, I keep the seating depth (0.010") at the same value for all the rounds and just change the amount of powder.
The loads with most consistent SD in velocity usually also get very tight groups. For me, there was no reason to change the seating depth so far.

But I've heard the statement, that it's possible to fine-tune the group size of a load, after you find one with a desired SD of muzzle velocity.

Now my question:

Doesn't a change in seating depth also change the pressure curve? At least according to Quickload, it does. I cannot imagine, how it's possible to tune just the group size with no change in SD of the velocities. Also the vibratory pattern could change, or?

 

[Kopfjager1]

The change in MV by changing seating depth is minimal. If you have an ES between 10-20 you may not see a difference in the average.
When I adjusted my seating depth, I saw a change of about 6 fps in my averages (5 rounds each group) from 2.22 BTO to 2.19 BTO. 2808 fps at 2.22" and 2802 fps at 2.19". ES of the 35 rounds fired was 21.